I've just upgraded from 11.10 to 12.04 and I'm seeing console output on my X screen. It's not legible but sometimes I can even see the cursor blinking. I'm also running a multi-seat system and I see garbage on the screen when someone types on the second keyboard as well. Clicking on the screen erases the garbage console output but it comes right back when someone starts typing.
xorg.conf
Section "ServerLayout"
Identifier "Desktop"
Screen 0 "DesktopScreen" 0 0
InputDevice "DesktopMouse" "CorePointer"
InputDevice "DesktopKeyboard" "CoreKeyboard"
Option "AutoAddDevices" "false"
Option "AllowEmptyInput" "true"
Option "AutoEnableDevices" "false"
EndSection
Section "ServerLayout"
Identifier "Desktop2"
Screen 1 "Desktop2Screen" 0 0
InputDevice "Desktop2Mouse" "CorePointer"
InputDevice "Desktop2Keyboard" "CoreKeyboard"
Option "AutoAddDevices" "false"
Option "AllowEmptyInput" "true"
Option "AutoEnableDevices" "false"
EndSection
Section "Module"
Load "dbe"
Load "extmod"
Load "type1"
Load "freetype"
Load "glx"
EndSection
Section "Files"
EndSection
Section "ServerFlags"
Option "AutoAddDevices" "false"
Option "AutoEnableDevices" "false"
Option "AllowMouseOpenFail" "on"
Option "AllowEmptyInput" "on"
Option "ZapWarning" "on"
Option "HandleSepcialKeys" "off" # Zapping on
Option "DRI2" "on"
Option "Xinerama" "0"
EndSection
# Desktop Mouse
Section "InputDevice"
Identifier "DesktopMouse"
Driver "evdev"
Option "Device" "/dev/input/event3"
Option "Protocol" "auto"
Option "GrabDevice" "on"
Option "Emulate3Buttons" "no"
Option "Buttons" "5"
Option "ZAxisMapping" "4 5"
Option "SendCoreEvents" "true"
EndSection
# Desktop2 Mouse
Section "InputDevice"
Identifier "Desktop2Mouse"
Driver "evdev"
Option "Device" "/dev/input/event5"
Option "Protocol" "auto"
Option "GrabDevice" "on"
Option "Emulate3Buttons" "no"
Option "Buttons" "5"
Option "ZAxisMapping" "4 5"
Option "SendCoreEvents" "true"
EndSection
Section "InputDevice"
Identifier "DesktopKeyboard"
Driver "evdev"
Option "Device" "/dev/input/event4"
Option "XkbRules" "xorg"
Option "XkbModel" "105"
Option "XkbLayout" "us"
Option "Protocol" "Standard"
EndSection
Section "InputDevice"
Identifier "Desktop2Keyboard"
Driver "evdev"
Option "Device" "/dev/input/event14"
Option "XkbRules" "xorg"
Option "XkbModel" "105"
Option "XkbLayout" "us"
Option "Protocol" "Standard"
EndSection
Section "Monitor"
Identifier "Desktop2Monitor"
VendorName "Acer"
ModelName "Acer G235H"
HorizSync 30.0 - 83.0
VertRefresh 56.0 - 75.0
Option "DPMS"
EndSection
Section "Monitor"
Identifier "DesktopMonitor"
VendorName "Acer"
ModelName "Acer H213H"
HorizSync 30.0 - 83.0
VertRefresh 56.0 - 75.0
Option "DPMS"
EndSection
Section "Device"
Identifier "EVGACard"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GTX 560 Ti"
Option "Coolbits" "1"
BusID "PCI:2:0:0"
Screen 0
EndSection
Section "Device"
Identifier "XFXCard"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GTX 9800"
Option "Coolbits" "1"
BusID "PCI:5:0:0"
Screen 0
EndSection
Section "Screen"
Identifier "DesktopScreen"
Device "EVGACard"
Monitor "DesktopMonitor"
DefaultDepth 24
SubSection "Display"
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Desktop2Screen"
Device "XFXCard"
Monitor "Desktop2Monitor"
DefaultDepth 24
SubSection "Display"
Depth 24
EndSubSection
EndSection
lightdm.conf
[SeatDefaults]
greeter-session=unity-greeter
#greeter-session=lightdm-razor-greeter
user-session=ubuntu
xserver-allow-tcp=false
xserver-pass-seat-name=true
greeter-pass-seat-id=true
[Seat:0]
xserver-layout=Desktop
xserver-command=/usr/bin/X :0 -layout Desktop -auth /var/run/lightdm/root/:0 -nolisten tcp vt8 -novtswitch -sharevts -background none
[Seat:1]
xserver-layout=Desktop2
xserver-command=/usr/bin/X :1 -layout Desktop2 -auth /var/run/lightdm/root/:1 -nolisten tcp vt9 -novtswitch -sharevts
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